The Census Users Dictionary is a comprehensive dictionary of geographic, population, and housing concepts for which data are collected and presented by the Bureau of the Census. The Dictionary is designed to be a convenient standard reference to facilitate accurate communication among users, between users and the Census Bureau, and within the Bureau itself. The Dictionary may also serve users as a general guide to available census tabulations.

Population and housing concept titles in this Dictionary reflect terminology used in the technical documentation of 1970 census summary tapes. Specific concept title wording which will be used in census printed reports is, in some cases, still being developed at the time of this writing and may differ from that in the technical documentation. Similarly, the wording of concept definitions which will appear in printed reports may reflect modifications resulting from continued review during the coming months.

Definitions in the Census Users Dictionary largely concern those subject concepts employed in the population and housing censuses. Concepts relating to the other censuses may be added at a later date. The Dictionary also includes a section (Part I) which presents definitions of geographic areas recognized in tabulations of all censuses.

Several aspects of 1970 census collection and processing procedures affect concept definitions and merit a brief mention at this point.

Collection. Certain questions on the census form are not designed strictly for tabulation purposes. Some of these questions, such as the respondents name, are included only to aid in checking completeness of enumeration. Other questions may be worded so as to increase the probability of reliable responses, for example, asking data of birth as well as age in years. Finally, some concepts tabulated are derived not from a direct question but inferred from one or more items more readily understood by the respondent, i.e., family-type tabulations are a product of questions on an individual's age and relationship to the head of the household.

Processing. Census questionnaires are not simply processed as they stand. Extensive editing procedures (computerized for the most part) are employed to render the data as complete and accurate as possible. Inconsistent answers are reconciled according to fixed editing rules. Missing entries are filled in according to set criteria. Characteristics of the universe are estimated from sample information.

Computers read edited responses onto basic record tapes, so called because they contain information about individual units enumerated (persons, households, and housing units in the case of the census of population and housing). Basic record data are then tabulated or summarized on summary tapes which are used to produce the final printed results. Because of the summarization of data items, data categories carried in the end products of the census may differ from the categories carried in the basic record tapes.

The collection and processing procedures involved in an operation of such massive proportions as the 1970 Census of Population and Housing are necessarily complex. The implications for concept definitions, such as those just mentioned, will be of differing importance to data users depending upon their plans for employing the data.

First, all users require concise, basic definitions of census concepts which appear in the tabulations the Bureau makes generally available; i.e., in printed reports, on summary tapes, and microfilm.

Second, there is a subcategory of users which finds knowledge of changes or additions in concept definitions throughout the census process important as a guide to the availability of additional information. The Census Bureau can make available, at user expense, special tabulations from the basic record tapes to produce different breakdowns or combinations of data categories to user specifications. However, no data is released that violates the confidentiality of an individual.

Finally, a small segment of data users requires detailed information regarding operational considerations affecting census concepts in order to apply sophisticated techniques of analysis to the data or to relate their own data to census statistics. This group may need to know, for instance, the percentage of nonresponse to a question and what was done about the missing information.

This Dictionary meets the general need for basic definitions of census concepts and furnishes information of value to persons planning requests for special tabulations from the Bureau. Requirements for more detailed information on census procedures as they affect concept definitions will be met later through papers and reports published by the Bureau and responses to inquiries from data users.

The Census Users Dictionary is organized to facilitate user understanding of census statistics. There is a part for geographic area definitions and separate parts for concept definitions associated with population and housing data. Each part includes an introductory discussion of collection and processing procedures and other considerations which affect concept meanings and the availability of information. Within each part, concept definitions are organized into broad subjects, such as family structure or occupancy status, generally in the order in which they appear in census publications. Each part is assigned a series of numbers to be used with each definition. Those numbers not used are available for future concept additions. For example, Part I is assigned concepts 1 through 49 but the concepts run only through number 35.

Note that only concepts which appear in connection with tabulated results receive identifying numbers. Additional concepts or categories carried on basic record tapes or census schedules are indicated in the text of appropriate numbered concepts definitions. Numbers are assigned to indicate the conceptual logic and structure of census categorization. Concepts which logically stand alone and do not constitute subcategories of other concepts, for example, sex or type of foundation in a housing unit, receive whole numbers (59 and 170 respectively). Subcategories of these concepts, such as male and female for sex, are indented under the main concept and receive suffix numbers (59.1 and 59.2 respectively). It is possible for a concept to be broken down in this manner into many sublevels of categorization. Words and phrases which appear in bold or are underlined are, in most cases, census concepts ( vacancy status, family type, urbanized area) or sub-categories of concepts ( vacant year-round units, husband-wife families, urban fringe). To aid the user in quickly locating a desired concept or category, an Alphabetical Index is appended to the Dictionary.

The text of concept definitions usually proceeds from the basic to the complex. Users who only require a general idea of a concept, such as household relationship or tenure status of occupied housing units, need not look further than the first sentence or paragraph in most instances. Users who want to know what questionnaire categories the concept is derived from, what additional categories are available, and so on, must look further.

Concept definitions include information derived from instructions to respondents and enumerators which affect concept meanings and, in many cases, information about the progress of a concept from questionnaire categories to processing categories to final tabulations. However, definitions are not completely operational. Precise details on editing and allocation procedures are not supplied.